I had a similar problem in Winter last year. In the end I wore some cream coloured pants and a white "hoodie" with a white t-shirt underneath. I'm not sure whether it was a no-no or not but during the meditation I actually had the hood on because it was so cold and as you can see from my profile picture, I have very short hair. No one seemed to think there was any problem with anything and earlier correspondence with the abbot suggested that comfort and practicality was as much a criteria as anything else... make sure you're warm, he said.
Through corruption of the Dhamma comes corruption of the discipline, and from corruption of the discipline comes corruption of the Dhamma. This is the first future danger as yet unarisen that will arise in the future. You should recognize it and make an effort to prevent it. (AN 5.79)
Neither traceable in the Discourses nor verifiable by the Discipline, one must conclude thus: 'Certainly, this is not the Blessed One's utterance; this has been misunderstood by that bhikkhu — or by that community, or by those elders, or by that elder.' In that way, bhikkhus, you should reject it. (DN 16)